(a) Field of the Invention
The present invention relates to frames and a dedicated channel which are used for talk-around direct communication.
(b) Description of the Related Art
IEEE 802.16n can be used to build a reliable wireless network even in emergency situations, based on WiBro technology. One of the key features of IEEE 802.16n is the talk-around direct communication (TDC) feature.
In an IEEE 802.16n system, some of infrastructure communication resources can be assigned to terminals performing direct communication, in order to provide talk-around direct communication. Frames used for talk-around direct communication include resources (channels) assigned in the IEEE 802.16n system, and the resources (channels) include a synchronization channel, a dedicated channel, and a supplementary channel. The dedicated channel may be used for data transmission and reception between terminals. FIG. 1 is a view showing terminals interfering with each other in talk-around direct communication.
However, there are some problems in current permutated dedicated channel structures. If high-reliability mobile stations (HR-MSs) are synchronized by a distributed synchronization method, the HR-MSs may have different timing/frequency offsets.
Also, if the HR-MSs are positioned adjacent to each other, interference may occur due to the difference in power level between the dedicated channels used by the HR-MSs. Referring to FIG. 1, mobile station (MS) a1 is positioned adjacent to MS b1, and therefore cannot use a TDC link (a) due to a TDC link (b) between MS b1 and MS b2.
Accordingly, it is necessary to modify the dedicated channel structure to solve this problem occurring in the prior art.